Antiviral compounds designated by the project officer at NIH-NIAID will be evaluated for toxicity, therapy, and prophylaxis against one or more feline viruses causing respiratory disease. Viruses to be tested include feline picornavirus (model for human cold), feline herpes virus (model for herpes simplex or other herpes viruses), and influenza A2 (model for influenza). Feline leukemiasarcoma viruses and feline panleukopenia virus (model for parvoviruses such as hepatitis or acute gastroenteritis), will be tested if designated by the project officer.